MacOSKeychainAPIChecker.cpp revision 243830
1226586Sdim//==--- MacOSKeychainAPIChecker.cpp ------------------------------*- C++ -*-==// 2226586Sdim// 3226586Sdim// The LLVM Compiler Infrastructure 4226586Sdim// 5226586Sdim// This file is distributed under the University of Illinois Open Source 6226586Sdim// License. See LICENSE.TXT for details. 7226586Sdim// 8226586Sdim//===----------------------------------------------------------------------===// 9226586Sdim// This checker flags misuses of KeyChainAPI. In particular, the password data 10226586Sdim// allocated/returned by SecKeychainItemCopyContent, 11226586Sdim// SecKeychainFindGenericPassword, SecKeychainFindInternetPassword functions has 12226586Sdim// to be freed using a call to SecKeychainItemFreeContent. 13226586Sdim//===----------------------------------------------------------------------===// 14226586Sdim 15226586Sdim#include "ClangSACheckers.h" 16226586Sdim#include "clang/StaticAnalyzer/Core/Checker.h" 17226586Sdim#include "clang/StaticAnalyzer/Core/CheckerManager.h" 18226586Sdim#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 19226586Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 20226586Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 21226586Sdim#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h" 22234353Sdim#include "llvm/ADT/SmallString.h" 23226586Sdim 24226586Sdimusing namespace clang; 25226586Sdimusing namespace ento; 26226586Sdim 27226586Sdimnamespace { 28226586Sdimclass MacOSKeychainAPIChecker : public Checker<check::PreStmt<CallExpr>, 29226586Sdim check::PreStmt<ReturnStmt>, 30226586Sdim check::PostStmt<CallExpr>, 31226586Sdim check::EndPath, 32226586Sdim check::DeadSymbols> { 33234353Sdim mutable OwningPtr<BugType> BT; 34226586Sdim 35226586Sdimpublic: 36226586Sdim /// AllocationState is a part of the checker specific state together with the 37226586Sdim /// MemRegion corresponding to the allocated data. 38226586Sdim struct AllocationState { 39226586Sdim /// The index of the allocator function. 40226586Sdim unsigned int AllocatorIdx; 41226586Sdim SymbolRef Region; 42226586Sdim 43226586Sdim AllocationState(const Expr *E, unsigned int Idx, SymbolRef R) : 44226586Sdim AllocatorIdx(Idx), 45226586Sdim Region(R) {} 46226586Sdim 47226586Sdim bool operator==(const AllocationState &X) const { 48226586Sdim return (AllocatorIdx == X.AllocatorIdx && 49226586Sdim Region == X.Region); 50226586Sdim } 51226586Sdim 52226586Sdim void Profile(llvm::FoldingSetNodeID &ID) const { 53226586Sdim ID.AddInteger(AllocatorIdx); 54226586Sdim ID.AddPointer(Region); 55226586Sdim } 56226586Sdim }; 57226586Sdim 58226586Sdim void checkPreStmt(const CallExpr *S, CheckerContext &C) const; 59226586Sdim void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const; 60226586Sdim void checkPostStmt(const CallExpr *S, CheckerContext &C) const; 61226586Sdim void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const; 62234353Sdim void checkEndPath(CheckerContext &C) const; 63226586Sdim 64226586Sdimprivate: 65226586Sdim typedef std::pair<SymbolRef, const AllocationState*> AllocationPair; 66226586Sdim typedef llvm::SmallVector<AllocationPair, 2> AllocationPairVec; 67226586Sdim 68226586Sdim enum APIKind { 69226586Sdim /// Denotes functions tracked by this checker. 70226586Sdim ValidAPI = 0, 71226586Sdim /// The functions commonly/mistakenly used in place of the given API. 72226586Sdim ErrorAPI = 1, 73226586Sdim /// The functions which may allocate the data. These are tracked to reduce 74226586Sdim /// the false alarm rate. 75226586Sdim PossibleAPI = 2 76226586Sdim }; 77226586Sdim /// Stores the information about the allocator and deallocator functions - 78226586Sdim /// these are the functions the checker is tracking. 79226586Sdim struct ADFunctionInfo { 80226586Sdim const char* Name; 81226586Sdim unsigned int Param; 82226586Sdim unsigned int DeallocatorIdx; 83226586Sdim APIKind Kind; 84226586Sdim }; 85226586Sdim static const unsigned InvalidIdx = 100000; 86226586Sdim static const unsigned FunctionsToTrackSize = 8; 87226586Sdim static const ADFunctionInfo FunctionsToTrack[FunctionsToTrackSize]; 88226586Sdim /// The value, which represents no error return value for allocator functions. 89226586Sdim static const unsigned NoErr = 0; 90226586Sdim 91226586Sdim /// Given the function name, returns the index of the allocator/deallocator 92226586Sdim /// function. 93226586Sdim static unsigned getTrackedFunctionIndex(StringRef Name, bool IsAllocator); 94226586Sdim 95226586Sdim inline void initBugType() const { 96226586Sdim if (!BT) 97226586Sdim BT.reset(new BugType("Improper use of SecKeychain API", "Mac OS API")); 98226586Sdim } 99226586Sdim 100226586Sdim void generateDeallocatorMismatchReport(const AllocationPair &AP, 101226586Sdim const Expr *ArgExpr, 102226586Sdim CheckerContext &C) const; 103226586Sdim 104234353Sdim /// Find the allocation site for Sym on the path leading to the node N. 105234353Sdim const Stmt *getAllocationSite(const ExplodedNode *N, SymbolRef Sym, 106234353Sdim CheckerContext &C) const; 107234353Sdim 108226586Sdim BugReport *generateAllocatedDataNotReleasedReport(const AllocationPair &AP, 109234353Sdim ExplodedNode *N, 110234353Sdim CheckerContext &C) const; 111226586Sdim 112226586Sdim /// Check if RetSym evaluates to an error value in the current state. 113226586Sdim bool definitelyReturnedError(SymbolRef RetSym, 114234353Sdim ProgramStateRef State, 115226586Sdim SValBuilder &Builder, 116226586Sdim bool noError = false) const; 117226586Sdim 118226586Sdim /// Check if RetSym evaluates to a NoErr value in the current state. 119226586Sdim bool definitelyDidnotReturnError(SymbolRef RetSym, 120234353Sdim ProgramStateRef State, 121226586Sdim SValBuilder &Builder) const { 122226586Sdim return definitelyReturnedError(RetSym, State, Builder, true); 123226586Sdim } 124234353Sdim 125234353Sdim /// Mark an AllocationPair interesting for diagnostic reporting. 126234353Sdim void markInteresting(BugReport *R, const AllocationPair &AP) const { 127234353Sdim R->markInteresting(AP.first); 128234353Sdim R->markInteresting(AP.second->Region); 129234353Sdim } 130226586Sdim 131226586Sdim /// The bug visitor which allows us to print extra diagnostics along the 132226586Sdim /// BugReport path. For example, showing the allocation site of the leaked 133226586Sdim /// region. 134234353Sdim class SecKeychainBugVisitor 135234353Sdim : public BugReporterVisitorImpl<SecKeychainBugVisitor> { 136226586Sdim protected: 137226586Sdim // The allocated region symbol tracked by the main analysis. 138226586Sdim SymbolRef Sym; 139226586Sdim 140226586Sdim public: 141226586Sdim SecKeychainBugVisitor(SymbolRef S) : Sym(S) {} 142226586Sdim virtual ~SecKeychainBugVisitor() {} 143226586Sdim 144226586Sdim void Profile(llvm::FoldingSetNodeID &ID) const { 145226586Sdim static int X = 0; 146226586Sdim ID.AddPointer(&X); 147226586Sdim ID.AddPointer(Sym); 148226586Sdim } 149226586Sdim 150226586Sdim PathDiagnosticPiece *VisitNode(const ExplodedNode *N, 151226586Sdim const ExplodedNode *PrevN, 152226586Sdim BugReporterContext &BRC, 153226586Sdim BugReport &BR); 154226586Sdim }; 155226586Sdim}; 156226586Sdim} 157226586Sdim 158226586Sdim/// ProgramState traits to store the currently allocated (and not yet freed) 159226586Sdim/// symbols. This is a map from the allocated content symbol to the 160226586Sdim/// corresponding AllocationState. 161243830SdimREGISTER_MAP_WITH_PROGRAMSTATE(AllocatedData, 162243830Sdim SymbolRef, 163243830Sdim MacOSKeychainAPIChecker::AllocationState) 164226586Sdim 165226586Sdimstatic bool isEnclosingFunctionParam(const Expr *E) { 166226586Sdim E = E->IgnoreParenCasts(); 167226586Sdim if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) { 168226586Sdim const ValueDecl *VD = DRE->getDecl(); 169226586Sdim if (isa<ImplicitParamDecl>(VD) || isa<ParmVarDecl>(VD)) 170226586Sdim return true; 171226586Sdim } 172226586Sdim return false; 173226586Sdim} 174226586Sdim 175226586Sdimconst MacOSKeychainAPIChecker::ADFunctionInfo 176226586Sdim MacOSKeychainAPIChecker::FunctionsToTrack[FunctionsToTrackSize] = { 177226586Sdim {"SecKeychainItemCopyContent", 4, 3, ValidAPI}, // 0 178226586Sdim {"SecKeychainFindGenericPassword", 6, 3, ValidAPI}, // 1 179226586Sdim {"SecKeychainFindInternetPassword", 13, 3, ValidAPI}, // 2 180226586Sdim {"SecKeychainItemFreeContent", 1, InvalidIdx, ValidAPI}, // 3 181226586Sdim {"SecKeychainItemCopyAttributesAndData", 5, 5, ValidAPI}, // 4 182226586Sdim {"SecKeychainItemFreeAttributesAndData", 1, InvalidIdx, ValidAPI}, // 5 183226586Sdim {"free", 0, InvalidIdx, ErrorAPI}, // 6 184226586Sdim {"CFStringCreateWithBytesNoCopy", 1, InvalidIdx, PossibleAPI}, // 7 185226586Sdim}; 186226586Sdim 187226586Sdimunsigned MacOSKeychainAPIChecker::getTrackedFunctionIndex(StringRef Name, 188226586Sdim bool IsAllocator) { 189226586Sdim for (unsigned I = 0; I < FunctionsToTrackSize; ++I) { 190226586Sdim ADFunctionInfo FI = FunctionsToTrack[I]; 191226586Sdim if (FI.Name != Name) 192226586Sdim continue; 193226586Sdim // Make sure the function is of the right type (allocator vs deallocator). 194226586Sdim if (IsAllocator && (FI.DeallocatorIdx == InvalidIdx)) 195226586Sdim return InvalidIdx; 196226586Sdim if (!IsAllocator && (FI.DeallocatorIdx != InvalidIdx)) 197226586Sdim return InvalidIdx; 198226586Sdim 199226586Sdim return I; 200226586Sdim } 201226586Sdim // The function is not tracked. 202226586Sdim return InvalidIdx; 203226586Sdim} 204226586Sdim 205226586Sdimstatic bool isBadDeallocationArgument(const MemRegion *Arg) { 206234353Sdim if (!Arg) 207234353Sdim return false; 208226586Sdim if (isa<AllocaRegion>(Arg) || 209226586Sdim isa<BlockDataRegion>(Arg) || 210226586Sdim isa<TypedRegion>(Arg)) { 211226586Sdim return true; 212226586Sdim } 213226586Sdim return false; 214226586Sdim} 215234353Sdim 216226586Sdim/// Given the address expression, retrieve the value it's pointing to. Assume 217226586Sdim/// that value is itself an address, and return the corresponding symbol. 218226586Sdimstatic SymbolRef getAsPointeeSymbol(const Expr *Expr, 219226586Sdim CheckerContext &C) { 220234353Sdim ProgramStateRef State = C.getState(); 221234353Sdim SVal ArgV = State->getSVal(Expr, C.getLocationContext()); 222226586Sdim 223226586Sdim if (const loc::MemRegionVal *X = dyn_cast<loc::MemRegionVal>(&ArgV)) { 224226586Sdim StoreManager& SM = C.getStoreManager(); 225234353Sdim SymbolRef sym = SM.getBinding(State->getStore(), *X).getAsLocSymbol(); 226234353Sdim if (sym) 227234353Sdim return sym; 228226586Sdim } 229226586Sdim return 0; 230226586Sdim} 231226586Sdim 232226586Sdim// When checking for error code, we need to consider the following cases: 233226586Sdim// 1) noErr / [0] 234226586Sdim// 2) someErr / [1, inf] 235226586Sdim// 3) unknown 236226586Sdim// If noError, returns true iff (1). 237226586Sdim// If !noError, returns true iff (2). 238226586Sdimbool MacOSKeychainAPIChecker::definitelyReturnedError(SymbolRef RetSym, 239234353Sdim ProgramStateRef State, 240226586Sdim SValBuilder &Builder, 241226586Sdim bool noError) const { 242226586Sdim DefinedOrUnknownSVal NoErrVal = Builder.makeIntVal(NoErr, 243226586Sdim Builder.getSymbolManager().getType(RetSym)); 244226586Sdim DefinedOrUnknownSVal NoErr = Builder.evalEQ(State, NoErrVal, 245226586Sdim nonloc::SymbolVal(RetSym)); 246234353Sdim ProgramStateRef ErrState = State->assume(NoErr, noError); 247226586Sdim if (ErrState == State) { 248226586Sdim return true; 249226586Sdim } 250226586Sdim 251226586Sdim return false; 252226586Sdim} 253226586Sdim 254226586Sdim// Report deallocator mismatch. Remove the region from tracking - reporting a 255226586Sdim// missing free error after this one is redundant. 256226586Sdimvoid MacOSKeychainAPIChecker:: 257226586Sdim generateDeallocatorMismatchReport(const AllocationPair &AP, 258226586Sdim const Expr *ArgExpr, 259226586Sdim CheckerContext &C) const { 260234353Sdim ProgramStateRef State = C.getState(); 261226586Sdim State = State->remove<AllocatedData>(AP.first); 262234353Sdim ExplodedNode *N = C.addTransition(State); 263226586Sdim 264226586Sdim if (!N) 265226586Sdim return; 266226586Sdim initBugType(); 267234353Sdim SmallString<80> sbuf; 268226586Sdim llvm::raw_svector_ostream os(sbuf); 269226586Sdim unsigned int PDeallocIdx = 270226586Sdim FunctionsToTrack[AP.second->AllocatorIdx].DeallocatorIdx; 271226586Sdim 272226586Sdim os << "Deallocator doesn't match the allocator: '" 273226586Sdim << FunctionsToTrack[PDeallocIdx].Name << "' should be used."; 274226586Sdim BugReport *Report = new BugReport(*BT, os.str(), N); 275226586Sdim Report->addVisitor(new SecKeychainBugVisitor(AP.first)); 276226586Sdim Report->addRange(ArgExpr->getSourceRange()); 277234353Sdim markInteresting(Report, AP); 278243830Sdim C.emitReport(Report); 279226586Sdim} 280226586Sdim 281226586Sdimvoid MacOSKeychainAPIChecker::checkPreStmt(const CallExpr *CE, 282226586Sdim CheckerContext &C) const { 283226586Sdim unsigned idx = InvalidIdx; 284234353Sdim ProgramStateRef State = C.getState(); 285226586Sdim 286239462Sdim const FunctionDecl *FD = C.getCalleeDecl(CE); 287239462Sdim if (!FD || FD->getKind() != Decl::Function) 288239462Sdim return; 289239462Sdim 290239462Sdim StringRef funName = C.getCalleeName(FD); 291234353Sdim if (funName.empty()) 292226586Sdim return; 293226586Sdim 294226586Sdim // If it is a call to an allocator function, it could be a double allocation. 295226586Sdim idx = getTrackedFunctionIndex(funName, true); 296226586Sdim if (idx != InvalidIdx) { 297226586Sdim const Expr *ArgExpr = CE->getArg(FunctionsToTrack[idx].Param); 298226586Sdim if (SymbolRef V = getAsPointeeSymbol(ArgExpr, C)) 299226586Sdim if (const AllocationState *AS = State->get<AllocatedData>(V)) { 300226586Sdim if (!definitelyReturnedError(AS->Region, State, C.getSValBuilder())) { 301226586Sdim // Remove the value from the state. The new symbol will be added for 302226586Sdim // tracking when the second allocator is processed in checkPostStmt(). 303226586Sdim State = State->remove<AllocatedData>(V); 304234353Sdim ExplodedNode *N = C.addTransition(State); 305226586Sdim if (!N) 306226586Sdim return; 307226586Sdim initBugType(); 308234353Sdim SmallString<128> sbuf; 309226586Sdim llvm::raw_svector_ostream os(sbuf); 310226586Sdim unsigned int DIdx = FunctionsToTrack[AS->AllocatorIdx].DeallocatorIdx; 311226586Sdim os << "Allocated data should be released before another call to " 312226586Sdim << "the allocator: missing a call to '" 313226586Sdim << FunctionsToTrack[DIdx].Name 314226586Sdim << "'."; 315226586Sdim BugReport *Report = new BugReport(*BT, os.str(), N); 316226586Sdim Report->addVisitor(new SecKeychainBugVisitor(V)); 317226586Sdim Report->addRange(ArgExpr->getSourceRange()); 318234353Sdim Report->markInteresting(AS->Region); 319243830Sdim C.emitReport(Report); 320226586Sdim } 321226586Sdim } 322226586Sdim return; 323226586Sdim } 324226586Sdim 325226586Sdim // Is it a call to one of deallocator functions? 326226586Sdim idx = getTrackedFunctionIndex(funName, false); 327226586Sdim if (idx == InvalidIdx) 328226586Sdim return; 329226586Sdim 330226586Sdim // Check the argument to the deallocator. 331226586Sdim const Expr *ArgExpr = CE->getArg(FunctionsToTrack[idx].Param); 332234353Sdim SVal ArgSVal = State->getSVal(ArgExpr, C.getLocationContext()); 333226586Sdim 334226586Sdim // Undef is reported by another checker. 335226586Sdim if (ArgSVal.isUndef()) 336226586Sdim return; 337226586Sdim 338234353Sdim SymbolRef ArgSM = ArgSVal.getAsLocSymbol(); 339226586Sdim 340226586Sdim // If the argument is coming from the heap, globals, or unknown, do not 341226586Sdim // report it. 342234353Sdim bool RegionArgIsBad = false; 343234353Sdim if (!ArgSM) { 344234353Sdim if (!isBadDeallocationArgument(ArgSVal.getAsRegion())) 345234353Sdim return; 346234353Sdim RegionArgIsBad = true; 347234353Sdim } 348226586Sdim 349226586Sdim // Is the argument to the call being tracked? 350226586Sdim const AllocationState *AS = State->get<AllocatedData>(ArgSM); 351226586Sdim if (!AS && FunctionsToTrack[idx].Kind != ValidAPI) { 352226586Sdim return; 353226586Sdim } 354226586Sdim // If trying to free data which has not been allocated yet, report as a bug. 355226586Sdim // TODO: We might want a more precise diagnostic for double free 356226586Sdim // (that would involve tracking all the freed symbols in the checker state). 357226586Sdim if (!AS || RegionArgIsBad) { 358226586Sdim // It is possible that this is a false positive - the argument might 359226586Sdim // have entered as an enclosing function parameter. 360226586Sdim if (isEnclosingFunctionParam(ArgExpr)) 361226586Sdim return; 362226586Sdim 363234353Sdim ExplodedNode *N = C.addTransition(State); 364226586Sdim if (!N) 365226586Sdim return; 366226586Sdim initBugType(); 367226586Sdim BugReport *Report = new BugReport(*BT, 368226586Sdim "Trying to free data which has not been allocated.", N); 369226586Sdim Report->addRange(ArgExpr->getSourceRange()); 370234353Sdim if (AS) 371234353Sdim Report->markInteresting(AS->Region); 372243830Sdim C.emitReport(Report); 373226586Sdim return; 374226586Sdim } 375226586Sdim 376226586Sdim // Process functions which might deallocate. 377226586Sdim if (FunctionsToTrack[idx].Kind == PossibleAPI) { 378226586Sdim 379226586Sdim if (funName == "CFStringCreateWithBytesNoCopy") { 380226586Sdim const Expr *DeallocatorExpr = CE->getArg(5)->IgnoreParenCasts(); 381226586Sdim // NULL ~ default deallocator, so warn. 382226586Sdim if (DeallocatorExpr->isNullPointerConstant(C.getASTContext(), 383226586Sdim Expr::NPC_ValueDependentIsNotNull)) { 384226586Sdim const AllocationPair AP = std::make_pair(ArgSM, AS); 385226586Sdim generateDeallocatorMismatchReport(AP, ArgExpr, C); 386226586Sdim return; 387226586Sdim } 388226586Sdim // One of the default allocators, so warn. 389226586Sdim if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(DeallocatorExpr)) { 390226586Sdim StringRef DeallocatorName = DE->getFoundDecl()->getName(); 391226586Sdim if (DeallocatorName == "kCFAllocatorDefault" || 392226586Sdim DeallocatorName == "kCFAllocatorSystemDefault" || 393226586Sdim DeallocatorName == "kCFAllocatorMalloc") { 394226586Sdim const AllocationPair AP = std::make_pair(ArgSM, AS); 395226586Sdim generateDeallocatorMismatchReport(AP, ArgExpr, C); 396226586Sdim return; 397226586Sdim } 398226586Sdim // If kCFAllocatorNull, which does not deallocate, we still have to 399226586Sdim // find the deallocator. Otherwise, assume that the user had written a 400226586Sdim // custom deallocator which does the right thing. 401226586Sdim if (DE->getFoundDecl()->getName() != "kCFAllocatorNull") { 402226586Sdim State = State->remove<AllocatedData>(ArgSM); 403226586Sdim C.addTransition(State); 404226586Sdim return; 405226586Sdim } 406226586Sdim } 407226586Sdim } 408226586Sdim return; 409226586Sdim } 410226586Sdim 411226586Sdim // The call is deallocating a value we previously allocated, so remove it 412226586Sdim // from the next state. 413226586Sdim State = State->remove<AllocatedData>(ArgSM); 414226586Sdim 415226586Sdim // Check if the proper deallocator is used. 416226586Sdim unsigned int PDeallocIdx = FunctionsToTrack[AS->AllocatorIdx].DeallocatorIdx; 417226586Sdim if (PDeallocIdx != idx || (FunctionsToTrack[idx].Kind == ErrorAPI)) { 418226586Sdim const AllocationPair AP = std::make_pair(ArgSM, AS); 419226586Sdim generateDeallocatorMismatchReport(AP, ArgExpr, C); 420226586Sdim return; 421226586Sdim } 422226586Sdim 423234353Sdim // If the buffer can be null and the return status can be an error, 424234353Sdim // report a bad call to free. 425234353Sdim if (State->assume(cast<DefinedSVal>(ArgSVal), false) && 426234353Sdim !definitelyDidnotReturnError(AS->Region, State, C.getSValBuilder())) { 427234353Sdim ExplodedNode *N = C.addTransition(State); 428226586Sdim if (!N) 429226586Sdim return; 430226586Sdim initBugType(); 431226586Sdim BugReport *Report = new BugReport(*BT, 432234353Sdim "Only call free if a valid (non-NULL) buffer was returned.", N); 433226586Sdim Report->addVisitor(new SecKeychainBugVisitor(ArgSM)); 434226586Sdim Report->addRange(ArgExpr->getSourceRange()); 435234353Sdim Report->markInteresting(AS->Region); 436243830Sdim C.emitReport(Report); 437226586Sdim return; 438226586Sdim } 439226586Sdim 440226586Sdim C.addTransition(State); 441226586Sdim} 442226586Sdim 443226586Sdimvoid MacOSKeychainAPIChecker::checkPostStmt(const CallExpr *CE, 444226586Sdim CheckerContext &C) const { 445234353Sdim ProgramStateRef State = C.getState(); 446239462Sdim const FunctionDecl *FD = C.getCalleeDecl(CE); 447239462Sdim if (!FD || FD->getKind() != Decl::Function) 448239462Sdim return; 449226586Sdim 450239462Sdim StringRef funName = C.getCalleeName(FD); 451239462Sdim 452226586Sdim // If a value has been allocated, add it to the set for tracking. 453226586Sdim unsigned idx = getTrackedFunctionIndex(funName, true); 454226586Sdim if (idx == InvalidIdx) 455226586Sdim return; 456226586Sdim 457226586Sdim const Expr *ArgExpr = CE->getArg(FunctionsToTrack[idx].Param); 458226586Sdim // If the argument entered as an enclosing function parameter, skip it to 459226586Sdim // avoid false positives. 460234353Sdim if (isEnclosingFunctionParam(ArgExpr) && 461234353Sdim C.getLocationContext()->getParent() == 0) 462226586Sdim return; 463226586Sdim 464226586Sdim if (SymbolRef V = getAsPointeeSymbol(ArgExpr, C)) { 465226586Sdim // If the argument points to something that's not a symbolic region, it 466226586Sdim // can be: 467226586Sdim // - unknown (cannot reason about it) 468226586Sdim // - undefined (already reported by other checker) 469226586Sdim // - constant (null - should not be tracked, 470226586Sdim // other constant will generate a compiler warning) 471226586Sdim // - goto (should be reported by other checker) 472226586Sdim 473226586Sdim // The call return value symbol should stay alive for as long as the 474226586Sdim // allocated value symbol, since our diagnostics depend on the value 475226586Sdim // returned by the call. Ex: Data should only be freed if noErr was 476226586Sdim // returned during allocation.) 477234353Sdim SymbolRef RetStatusSymbol = 478234353Sdim State->getSVal(CE, C.getLocationContext()).getAsSymbol(); 479226586Sdim C.getSymbolManager().addSymbolDependency(V, RetStatusSymbol); 480226586Sdim 481226586Sdim // Track the allocated value in the checker state. 482226586Sdim State = State->set<AllocatedData>(V, AllocationState(ArgExpr, idx, 483226586Sdim RetStatusSymbol)); 484226586Sdim assert(State); 485226586Sdim C.addTransition(State); 486226586Sdim } 487226586Sdim} 488226586Sdim 489226586Sdimvoid MacOSKeychainAPIChecker::checkPreStmt(const ReturnStmt *S, 490226586Sdim CheckerContext &C) const { 491226586Sdim const Expr *retExpr = S->getRetValue(); 492226586Sdim if (!retExpr) 493226586Sdim return; 494226586Sdim 495234353Sdim // If inside inlined call, skip it. 496234353Sdim const LocationContext *LC = C.getLocationContext(); 497234353Sdim if (LC->getParent() != 0) 498234353Sdim return; 499234353Sdim 500226586Sdim // Check if the value is escaping through the return. 501234353Sdim ProgramStateRef state = C.getState(); 502234353Sdim SymbolRef sym = state->getSVal(retExpr, LC).getAsLocSymbol(); 503234353Sdim if (!sym) 504226586Sdim return; 505234353Sdim state = state->remove<AllocatedData>(sym); 506226586Sdim 507226586Sdim // Proceed from the new state. 508226586Sdim C.addTransition(state); 509226586Sdim} 510226586Sdim 511234353Sdim// TODO: This logic is the same as in Malloc checker. 512234353Sdimconst Stmt * 513234353SdimMacOSKeychainAPIChecker::getAllocationSite(const ExplodedNode *N, 514234353Sdim SymbolRef Sym, 515234353Sdim CheckerContext &C) const { 516234353Sdim const LocationContext *LeakContext = N->getLocationContext(); 517234353Sdim // Walk the ExplodedGraph backwards and find the first node that referred to 518234353Sdim // the tracked symbol. 519234353Sdim const ExplodedNode *AllocNode = N; 520234353Sdim 521234353Sdim while (N) { 522234353Sdim if (!N->getState()->get<AllocatedData>(Sym)) 523234353Sdim break; 524234353Sdim // Allocation node, is the last node in the current context in which the 525234353Sdim // symbol was tracked. 526234353Sdim if (N->getLocationContext() == LeakContext) 527234353Sdim AllocNode = N; 528234353Sdim N = N->pred_empty() ? NULL : *(N->pred_begin()); 529234353Sdim } 530234353Sdim 531234353Sdim ProgramPoint P = AllocNode->getLocation(); 532239462Sdim if (CallExitEnd *Exit = dyn_cast<CallExitEnd>(&P)) 533239462Sdim return Exit->getCalleeContext()->getCallSite(); 534239462Sdim if (clang::PostStmt *PS = dyn_cast<clang::PostStmt>(&P)) 535239462Sdim return PS->getStmt(); 536239462Sdim return 0; 537234353Sdim} 538234353Sdim 539226586SdimBugReport *MacOSKeychainAPIChecker:: 540226586Sdim generateAllocatedDataNotReleasedReport(const AllocationPair &AP, 541234353Sdim ExplodedNode *N, 542234353Sdim CheckerContext &C) const { 543226586Sdim const ADFunctionInfo &FI = FunctionsToTrack[AP.second->AllocatorIdx]; 544226586Sdim initBugType(); 545234353Sdim SmallString<70> sbuf; 546226586Sdim llvm::raw_svector_ostream os(sbuf); 547226586Sdim os << "Allocated data is not released: missing a call to '" 548226586Sdim << FunctionsToTrack[FI.DeallocatorIdx].Name << "'."; 549234353Sdim 550234353Sdim // Most bug reports are cached at the location where they occurred. 551234353Sdim // With leaks, we want to unique them by the location where they were 552234353Sdim // allocated, and only report a single path. 553234353Sdim PathDiagnosticLocation LocUsedForUniqueing; 554234353Sdim if (const Stmt *AllocStmt = getAllocationSite(N, AP.first, C)) 555234353Sdim LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocStmt, 556234353Sdim C.getSourceManager(), N->getLocationContext()); 557234353Sdim 558234353Sdim BugReport *Report = new BugReport(*BT, os.str(), N, LocUsedForUniqueing); 559226586Sdim Report->addVisitor(new SecKeychainBugVisitor(AP.first)); 560234353Sdim markInteresting(Report, AP); 561226586Sdim return Report; 562226586Sdim} 563226586Sdim 564226586Sdimvoid MacOSKeychainAPIChecker::checkDeadSymbols(SymbolReaper &SR, 565226586Sdim CheckerContext &C) const { 566234353Sdim ProgramStateRef State = C.getState(); 567243830Sdim AllocatedDataTy ASet = State->get<AllocatedData>(); 568226586Sdim if (ASet.isEmpty()) 569226586Sdim return; 570226586Sdim 571226586Sdim bool Changed = false; 572226586Sdim AllocationPairVec Errors; 573243830Sdim for (AllocatedDataTy::iterator I = ASet.begin(), E = ASet.end(); I != E; ++I) { 574226586Sdim if (SR.isLive(I->first)) 575226586Sdim continue; 576226586Sdim 577226586Sdim Changed = true; 578226586Sdim State = State->remove<AllocatedData>(I->first); 579226586Sdim // If the allocated symbol is null or if the allocation call might have 580226586Sdim // returned an error, do not report. 581243830Sdim ConstraintManager &CMgr = State->getConstraintManager(); 582243830Sdim ConditionTruthVal AllocFailed = CMgr.isNull(State, I.getKey()); 583243830Sdim if (AllocFailed.isConstrainedTrue() || 584226586Sdim definitelyReturnedError(I->second.Region, State, C.getSValBuilder())) 585226586Sdim continue; 586226586Sdim Errors.push_back(std::make_pair(I->first, &I->second)); 587226586Sdim } 588234353Sdim if (!Changed) { 589234353Sdim // Generate the new, cleaned up state. 590234353Sdim C.addTransition(State); 591226586Sdim return; 592234353Sdim } 593226586Sdim 594234353Sdim static SimpleProgramPointTag Tag("MacOSKeychainAPIChecker : DeadSymbolsLeak"); 595234353Sdim ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag); 596226586Sdim 597226586Sdim // Generate the error reports. 598226586Sdim for (AllocationPairVec::iterator I = Errors.begin(), E = Errors.end(); 599226586Sdim I != E; ++I) { 600243830Sdim C.emitReport(generateAllocatedDataNotReleasedReport(*I, N, C)); 601226586Sdim } 602234353Sdim 603234353Sdim // Generate the new, cleaned up state. 604234353Sdim C.addTransition(State, N); 605226586Sdim} 606226586Sdim 607226586Sdim// TODO: Remove this after we ensure that checkDeadSymbols are always called. 608234353Sdimvoid MacOSKeychainAPIChecker::checkEndPath(CheckerContext &C) const { 609234353Sdim ProgramStateRef state = C.getState(); 610234353Sdim 611234353Sdim // If inside inlined call, skip it. 612234353Sdim if (C.getLocationContext()->getParent() != 0) 613234353Sdim return; 614234353Sdim 615243830Sdim AllocatedDataTy AS = state->get<AllocatedData>(); 616226586Sdim if (AS.isEmpty()) 617226586Sdim return; 618226586Sdim 619226586Sdim // Anything which has been allocated but not freed (nor escaped) will be 620226586Sdim // found here, so report it. 621226586Sdim bool Changed = false; 622226586Sdim AllocationPairVec Errors; 623243830Sdim for (AllocatedDataTy::iterator I = AS.begin(), E = AS.end(); I != E; ++I ) { 624226586Sdim Changed = true; 625226586Sdim state = state->remove<AllocatedData>(I->first); 626226586Sdim // If the allocated symbol is null or if error code was returned at 627226586Sdim // allocation, do not report. 628243830Sdim ConstraintManager &CMgr = state->getConstraintManager(); 629243830Sdim ConditionTruthVal AllocFailed = CMgr.isNull(state, I.getKey()); 630243830Sdim if (AllocFailed.isConstrainedTrue() || 631226586Sdim definitelyReturnedError(I->second.Region, state, 632234353Sdim C.getSValBuilder())) { 633226586Sdim continue; 634226586Sdim } 635226586Sdim Errors.push_back(std::make_pair(I->first, &I->second)); 636226586Sdim } 637226586Sdim 638226586Sdim // If no change, do not generate a new state. 639234353Sdim if (!Changed) { 640234353Sdim C.addTransition(state); 641226586Sdim return; 642234353Sdim } 643226586Sdim 644234353Sdim static SimpleProgramPointTag Tag("MacOSKeychainAPIChecker : EndPathLeak"); 645234353Sdim ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag); 646226586Sdim 647226586Sdim // Generate the error reports. 648226586Sdim for (AllocationPairVec::iterator I = Errors.begin(), E = Errors.end(); 649226586Sdim I != E; ++I) { 650243830Sdim C.emitReport(generateAllocatedDataNotReleasedReport(*I, N, C)); 651226586Sdim } 652234353Sdim 653234353Sdim C.addTransition(state, N); 654226586Sdim} 655226586Sdim 656226586Sdim 657226586SdimPathDiagnosticPiece *MacOSKeychainAPIChecker::SecKeychainBugVisitor::VisitNode( 658226586Sdim const ExplodedNode *N, 659226586Sdim const ExplodedNode *PrevN, 660226586Sdim BugReporterContext &BRC, 661226586Sdim BugReport &BR) { 662226586Sdim const AllocationState *AS = N->getState()->get<AllocatedData>(Sym); 663226586Sdim if (!AS) 664226586Sdim return 0; 665226586Sdim const AllocationState *ASPrev = PrevN->getState()->get<AllocatedData>(Sym); 666226586Sdim if (ASPrev) 667226586Sdim return 0; 668226586Sdim 669226586Sdim // (!ASPrev && AS) ~ We started tracking symbol in node N, it must be the 670226586Sdim // allocation site. 671226586Sdim const CallExpr *CE = cast<CallExpr>(cast<StmtPoint>(N->getLocation()) 672226586Sdim .getStmt()); 673226586Sdim const FunctionDecl *funDecl = CE->getDirectCallee(); 674226586Sdim assert(funDecl && "We do not support indirect function calls as of now."); 675226586Sdim StringRef funName = funDecl->getName(); 676226586Sdim 677226586Sdim // Get the expression of the corresponding argument. 678226586Sdim unsigned Idx = getTrackedFunctionIndex(funName, true); 679226586Sdim assert(Idx != InvalidIdx && "This should be a call to an allocator."); 680226586Sdim const Expr *ArgExpr = CE->getArg(FunctionsToTrack[Idx].Param); 681226586Sdim PathDiagnosticLocation Pos(ArgExpr, BRC.getSourceManager(), 682226586Sdim N->getLocationContext()); 683226586Sdim return new PathDiagnosticEventPiece(Pos, "Data is allocated here."); 684226586Sdim} 685226586Sdim 686226586Sdimvoid ento::registerMacOSKeychainAPIChecker(CheckerManager &mgr) { 687226586Sdim mgr.registerChecker<MacOSKeychainAPIChecker>(); 688226586Sdim} 689